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Seif Habbachi

@seifhabbachi

Lead fullstack developer (backend & DevOps), freelance with Cantem. Node.js, NestJS, Next.js, AWS and LLM products, shipped end to end.

France

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What I'm looking for

Freelance / contract missions as a lead fullstack or backend developer: Node.js, NestJS, Next.js, AWS and AI / LLM products. Daily rate from 500 EUR. Remote, or on-site in Paris / Ile-de-France. Best fit: SaaS, AI, fintech or deeptech teams that need a senior to ship a complete platform, take over a legacy codebase or stabilize a critical product in production.

Lead fullstack developer specialised in backend and DevOps, with 10+ years of experience. I design and ship complete platforms: Next.js and React Native front ends, Node.js and NestJS back ends, SQL and NoSQL databases, AWS cloud, Docker and Kubernetes, CI/CD. I have built and led technical teams in Agile and Scrum, taken over legacy codebases and stabilized high-load products.

Currently lead backend developer for a major carmaker, on an internal product platform used by thousands of employees: I joined the frontend team and became lead developer of the backend team on the critical stack, coordinating frontend, backend, data and infrastructure work and driving cross-team topics involving 100+ people.

AI products: Koncile (LLM analysis of invoices and expense reports, OpenSearch indexing, asynchronous AI document pipelines, CI/CD with Jest coverage above 90%), Jimini AI (legal LLM platform with document embeddings and AI chat, DevOps chain on GitHub Actions and Docker) and Arcads (AI video generation platform, front-end and back-end teams set up in Agile as Scrum Master, A/B testing).

High-traffic products: The Luck Factory, an online casino with 2 million international users (Twig to React migration, PHP 7 to 8 upgrade, rebuild of a wallet used by 700,000+ users), and TF1's streaming app on iOS and Android (live and on-demand video).

École 42 and Université Pierre-et-Marie-Curie (Paris 6) graduate. French native, fluent English. Member of Cantem, a collective of independent senior developers from École 42.

Experience

Work history, roles, and key accomplishments

Current

Lead Backend Developer

Current

Major carmaker (via an IT consultancy)

Aug 2025 - Present (1 year 2 months)

Node.js and AI contract for a major carmaker, through an IT consultancy. Internal product platform used by thousands of employees. Joined the frontend team, then became lead developer of the backend team on the critical stack. I coordinate frontend, backend, data and infrastructure work, arbitrate carmaker constraints and drive cross-team topics involving 100+ people.

React Next.js Node AI LLM TypeScript

Fullstack JS Developer, web and mobile

Arcads.ai

Jun 2024 - Jan 2025 (7 months)

AI platform that generates short-form and advertising videos. Designed user-centred UX/UI mockups and set up the frontend and backend teams in Agile, acting as Scrum Master. Ran A/B tests and tracked user KPIs to improve engagement, plus SEO optimisation.

Next.js TypeScript AWS NestJS SST Sequelize Zod

Fullstack JS Developer, frontend focus

Koncile.ai

Jan 2024 - Jul 2024 (6 months)

LLM-based analysis of expense reports and invoices, with automatic classification and enrichment. React and TypeScript dashboard deployed with SST on AWS. Modular Node.js backend, OpenSearch indexing and asynchronous AI document pipelines. Industrialised CI/CD with Jest test coverage above 90%, real-time monitoring and alerting.

Tailwind Node NestJS PostgreSQL OpenSearch SST AWS LLM React TypeScript

Fullstack JS Developer, DevOps Manager

Jimini AI

Jul 2023 - Dec 2023 (5 months)

LLM platform for legal professionals, with cloud storage and collaboration. Built the document embedding systems and the AI chat. Set up the DevOps chain: CI/CD on GitHub Actions, Docker, cron jobs.

Next.js AWS Lambda AWS CDK NestJS PostgreSQL TypeScript WebSockets

Lead Fullstack JS Developer

Jaylo

Aug 2022 - Feb 2023 (6 months)

Luxury product authentication: mobile app and generator of encrypted QR codes stored on a blockchain, used to verify the authenticity of luxury goods and official documents with a single scan.

Express React Native NodeJS Blockchain

Fullstack JS Developer, data collection

Combigo

Sep 2021 - Jun 2022 (9 months)

Eco-minded flight comparison engine: per-trip emissions calculation and multi-source data collection.

React JavaScript PHP C++Java

Backend Fullstack & DevOps Developer

The Luck Factory

Dec 2020 - Sep 2021 (9 months)

Online casino platform with 2 million international users. Migrated the frontend from Twig to React and upgraded PHP 7 to PHP 8. Rebuilt a wallet system used by more than 700,000 users; service development and debugging.

JavaScript React Symfony OpenSearch MySQL Redis Docker Kubernetes

Lead Developer

Le Big Day

Feb 2020 - Dec 2020 (10 months)

Ecosystem of three apps and two websites for personalised products: photo prints, calendars and photo books.

React Native JavaScript

Lead Fullstack Developer

TF1

Sep 2019 - Feb 2020 (5 months)

Streaming app of the TV channel on iOS and Android. Integrated live and on-demand video streams with advanced playback state management. Store releases and patches, working with product and QA.

React Native Redux TypeScript Axios Videojs Firebase